Hi Dan. I am having a similar issue to Jacob at the moment.
Are you suggesting here to apply this expression to the point control itself?
Am trying to have a trim path stroke loop using an offset, expression linked to a slider, but also want a few shape layers to loop with the stroke. Have tried using create nulls from paths (trace null) in order to parents the shapes to the null but can’t seem to find a way to get my null to loop with the stroke offset, as I normally just expression link the null to the start or end point of the trim.
Thank you in advance.